判断表中是否存在某个字段（列），不存在就添加

USE CCMPDB
GO
IF NOT EXISTS ( SELECT  *
                FROM    syscolumns
                WHERE   id = OBJECT_ID('TContract')
                        AND name = 'Contract_contractType' )
    BEGIN
        ALTER TABLE dbo.TContract ADD [Contract_contractType] VARCHAR(100) NULL
    END
GO